HDUOJ---Can you solve this equation?

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5667    Accepted Submission(s): 2681
http://acm.hdu.edu.cn/showproblem.php?pid=2199

Problem Description

Now,given the equation 8*x^4 + 7*x^3 + 2*x^2 + 3*x + 6 == Y,can you find its solution between 0 and 100;
Now please try your lucky.

 

 

Input

The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has a real number Y (fabs(Y) <= 1e10);

 

 

Output

For each test case, you should just output one real number(accurate up to 4 decimal places),which is the solution of the equation,or “No solution!”,if there is no solution for the equation between 0 and 100.

 

 

Sample Input

2 100 -4

 

 

Sample Output

1.6152 No solution!

 

 

Author

Redow

 

 

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代码：

#include<iostream>

#include<cstdio>

#define sum(x) ((8*x*x*x*x)+(7*x*x*x)+(2*x*x)+(3*x)+(6))

using namespace std;

int main()

{

    int t;

    double y,mid,left,right;

    cin>>t;

    while(t--)

    {

     scanf("%lf",&y);

     left=0.0,right=100.0;

     if(y>=6.0&&y<=sum(100))

     {

      while(right-left>1e-8)

      {

         mid=(left+right)/2.0;

             if(sum(mid)-y>1e-8)

             right=mid;

         else

             if(y-sum(mid)>1e-8)

                 left=mid;

             else 

                 break;

      } 

         printf("%.4lf\n",mid);

     }

     else

         puts("No solution!");

    }

    return 0;

}